The present invention relates to magnetic resonance imaging (MRI) systems. Receiving coils are used in MRI systems to intercept the radio frequency magnetic field generated by a human subject or object in the presence of a main magnetic field. Many coil designs exist for use in MRI systems, including what is often referred to as a “birdcage” coil. The birdcage coil has been described in the Journal of Magnetic Resonance (1985) 63:622-628 and U.S. Pat. No. 4,680,548 to Edelstein et al. FIG. 1 shows a standard birdcage coil having four conductive connection members connecting two circular conductive loops. Although four conductive connection members have been shown in FIG. 1, other numbers of conductive members can be used, such as two, six, or eight members. Each coil can be viewed as a separate quadrature coil system.
A spiral volume coil was introduced in April 1998 at the ISMRM meeting in Sydney, Australia by David Alsop and others from the University of Pennsylvania Medical Center. This new spiral volume coil replaced the straight conductive connection members of the standard birdcage with spiral conductive connection members. Others have utilized this spiral volume coil to achieve improved uniformity.